In the prior art, for a terminal that is simultaneously covered by multiple cells, a base station usually sends service data to the terminal by using only a spectrum occupied by a primary cell. When a resource of the spectrum occupied by the primary cell is relatively poor, for example, radio signal strength of the spectrum is relatively weak, and network uplink and downlink rates are relatively low, or when congestion occurs during service data transmission by the base station in the primary cell, how to use a spectrum occupied by another cell to send service data is not considered in the prior art. It can be learned that spectrum utilization in the prior art is relatively low.